1. Field of the Invention
This invention relates to a shift mechanism for an outboard motor.
2. Description of the Related Art
In outboard motor shift mechanisms, shift is usually changed by moving a shift rod having a cam at its distal end in the longitudinal direction to slide a shift slider such that a clutch is switched from its neutral position to a forward position where it engages with a forward gear or a reverse position where it engages with a reverse gear.
Alternatively, as shown in FIG. 13, a shift rod 200 is provided with a rod pin 202 at a position eccentric from the rod center 200c, in such a way that a shift slider 204 is slid to effect shift by a distance due to a displacement of the rod pin 202 caused by a rotation of the shift rod 200 in a direction indicated by an arrow. The distance of travel of the rod pin 2002 corresponds to a circular arc whose radius is the amount of eccentricity of the rod pin 202. The angle of rotation of the shift rod 200 (i.e., the displacement angle of the rod pin 202) when the clutch engages with the forward gear or reverse gear (more specifically, when the clutch is in-gear), is about plus/minus 30 degrees, when the neutral position of the rod pin 202 (shown by a phantom line) is defined as zero.
In the outboard motor shift mechanisms including that illustrated in FIG. 13, when the shift rod is operated manually, since the operator tends to have an unpleasant operation xe2x80x9cfeelxe2x80x9d owing to, for instance, heavy load, it has hitherto, been proposed installing an actuator at the hull and connecting it with the shift rod in the outboard motor through a cable or a link mechanism to power-assist the driving of the shift rod, i.e. the shift. The add-on system using such an actuator has disadvantages that its structure is complicated, that it adds to the number and weight of the components, and it needs a space for the actuator at the hull.
Moreover, since the angular range of rotation of the shift rod when the clutch is engaged (in-gear), approximately plus/minus 30 degrees as mentioned above, this causes the shift slider to produces a reaction force to return to the neutral position, that acts on the shift rod as a torque to rotate it. In order to ensure the xe2x80x9cin-gearxe2x80x9d state, it becomes necessary to add a retainer that can retain the shift rod at that angle against the force. This makes the structure more complicated and increases the number and weight of the components.
An object of the present invention is therefore to overcome the foregoing issues by providing a shift mechanism for an outboard motor that improves operation feel, is simply configured to avoid an increase in the number of components and weight, while avoiding a problem regarding space utilization.
In order to achieve the foregoing object, this invention provides a shift mechanism for an outboard motor mounted on a stern of a boat and having an internal combustion engine at its upper portion and a propeller at its lower portion that is powered by the engine to propel the boat, comprising: a clutch installed in the outboard motor to be engaged from a neutral position with at least one of a forward gear that causes the boat to be propelled in a forward direction and a reverse gear that causes the boat to be propelled in a direction reverse to the forward direction; a shift rod movably installed in the outboard motor; an actuator installed in the outboard motor to move the shift rod; and a shift slider, installed in the outboard and connected to the shift rod to slide to at least one of a position at which the clutch is engaged with the forward gear and a position at which the clutch is engaged with the reverse gear.